Energy consumption is becoming a factor in the design of all types of computer systems. In large-scale data centers, power can determine the maximum possible system sizes, and is also a major element of the operating costs. In mobile devices, the limited energy storage capacity of batteries requires very efficient operation to give acceptable battery lifetimes.
Modern hardware provides controls that allow tradeoffs between energy consumption and performance. For example, in order to reduce energy consumption, a processor clock rate can be reduced. When the clock rate is reduced, the processor supply voltage can also be reduced as the processor now has a longer cycle time allowing more time for logic gates to switch. This technique is known as Dynamic Voltage and Frequency Switching (DVFS). In another example, in mobile devices, displays may be dimmed to minimize energy consumption.